//Circle.h
#include<iostream>
using namespace std;
class Circle
{
public:
  Circle(void);
  Circle(float r);      //定义一个圆
  float getArea();      //圆的面积
  float getGirth();     //圆的周长
  static const  float PI ;
protected:
  float mR;             //圆的半径
};
const float Circle::PI=3.14;
Circle::Circle(void)
{
  mR=0;
}
Circle::Circle(float r):mR(r)
{
}
float Circle::getArea()
{
  return PI*mR*mR;
}
float Circle::getGirth()
{
  return 2*PI*mR;
}
//main.cpp
//#include"Cylinder.h"
//#include"Circle.h"
class Cylinder:public Circle
{
public:
  Cylinder(float t,float m):Circle(t)
  {
    mH=m;
  }
  float getArea()
  {
    return Circle::getGirth()*mH+2*Circle::getArea();
  }
  float getVol()
  {
    return Circle::getArea()*mH;
  }
private:
  float mH; 
};
//main.cpp
//#include"Cylinder.h"
//#include"Circle.h"
#include<iostream>
using namespace std;
int main()
{
  float t, m;
  cout << "请输入圆的半径：";
  cin >> t;                                       //键盘接收圆的半径
  Circle c1(t);
  cout <<"圆的面积为："<< c1.getArea() << endl;
  cout << "请输入圆柱的高：";
  cin >> m;                                       //键盘接收圆柱的高
  Cylinder c2(t, m);
  cout <<"圆柱的表面积为："<< c2.getArea() << endl;
  cout <<"圆柱的体积为："<< c2.getVol() << endl;
}

class Rect
{
public:
  Rect(float l, float w);            //定义矩形接受长和宽
  float getArea();                   //矩形面积
protected:
  float mLength;                      //定义长
  float mWidth;                       //定义宽
};
Rect::Rect(float l,float w)
{
  mLength=l;
  mWidth=w;
}
float Rect::getArea()
{
  return mLength*mWidth;
}
class cubiod:public Rect
{
  public:
    cubiod(float l,float w,float h);
    float getVol();
    float Area();
  private:
    float mHeight;
};
cubiod::cubiod(float l,float w,float h):Rect(l,w)
{
  mHeight=h;
}
float cubiod::getVol()
{
  return Rect::getArea()*this->mHeight;
}
float cubiod::Area()
{
  return 2*Rect::getArea()+2*this->mLength*this->mHeight+2*this->mWidth*this->mHeight;
}
#include<iostream>
using namespace std;
int main()
{
  int j, k, l;                                   
  cout << "请输入矩形的长和宽：";
  cin >> j >> k;                                            //键盘接收长和宽
  Rect r1(j, k);
  cout <<"矩形的面积为："<< r1.getArea() << endl;
  cout << "请输入立方体的高：";
  cin >> l;                                                 //接受高
  cubiod c1(j,k,l);
  cout <<"立方体体积为："<< c1.getVol() << endl;
  cout <<"立方体表面积为："<< c1.Area();
  return 0;
}

#include<iostream >
using namespace std;
class A{
public:
A(){cout<<“A”;}
~A(){cout<<“-A”;}
};
class B:public A{
A*p;
public:
B(){cout<<“B”;p=new A();}
~B(){cout<<“-B”;  delete p;}
};
int main()
{
B obj;
return 0;
}

#include<iostream >
using namespace std;
class Base{
public:
     void fun(){cost<<“Base::fun”<<endl;}
};
class Derived:public Base{
public:
void fun(){
_______________
cout<<“Derived::fun”<<endl;
}
};
int main() {
Derived d;
d.fun();
return 0;}